Mold making device having blow nozzle

ABSTRACT

A series of expendable shell molds is formed in a permanent pattern having a series of connected mold cavities. A passage including the cavities extends through the pattern. A swinging blow-vent nozzle is mounted at each end of the passage, the two nozzles being rotationally fixed to each other. In one position the first nozzle blows into the pattern while the second nozzle vents the pattern. In a second position the second nozzle blows into the pattern while the first nozzle vents the pattern. In a third position one of the nozzles blocks the passage while the other has been swung out of the way to provide access for a sand blow box which can then blow sand into the pattern. The nozzles are clamped against the pattern by a hydraulic cylinder which moves them toward each other on a shaft. The device includes means for separating the pattern, lifting the gang of molds out of the pattern and stripping the molds from pins on which they are formed or by which they are lifted. The device for elevating the finished molds includes means for blowing out the molds as the patterns are raised. The apparatus is particularly suitable for making cores for making tappet bodies and for making molds for casting engine valves.

[ 3,684,000 [451 Aug. 15, 1972 MOLD MAKING DEVICE HAVING PrimaryExaminer-4. Spencer Overholser BLOW NOZZLE Assistant Exarniner-John S.Brown 72 Inventor: Walter H. Van Deberg, Berkley, chslwlm [73 A Tho ManI I [57] ABS CT 1 1 u actunng A series of expendable shell molds isformed in a per- Co., Ferndale, Mich. t

. manent pattern having a series of connected mold S- 1969 v cavities. Apassage including the cavities extends through the pattern. A swingingblow-vent nozzle is mounted at each end of the passage, the two nozzlesbeing rotationally fixed to each other. in one position United StatesPatent Van Deberg 221 Filedi 211 Appl. No; 853,913

the first nozzle blows into the pattern while the second nozzle ventsthe pattern. In a second position the second nozzle blows into thepattern while the first nozzle vents the pattern. In a third positionone of the nozzles blocks the passage while the other has been swung outof the way to provide access for a sand blow box which can then blowsand into the pattern. The nozzles are clamped against the pattern by ahydraulic cylinder which moves them toward each other on a shaft. Thedevice includes means for lifting the gang of molds out of ping themolds from. pins on which they are formed or by which they are lifted.The device for elevating the finished molds includes means for blowingout the molds as the patterns are raised. The apparatus is particularlysuitable for making cores for making tappet bodies and for making moldsfor mm a u s v M m e 3 m .m gm g mm m a g m .m Pe w Rm c 9 1 7 3 i 000NHH 1 O OOO 90043 7277222 452 I r 66/// 61 3 9134M, 4 2444 .I. 03330/6//666 x 39 ,3 41 111 mz mz 6 m m mm 2 37 6 A 0 I m S mm m 7 ,8 m U U mm 222 9 uunnnuu muw337 m mummnnu 9 9 u u "u m..oo zuufLrn M A nnnn uen"0 33 O P u" d" m"2 Sm nnm 5 ..7.3 E o ak .4 m S1l l1 "#6 T 0fleehae "mm A DBhBCCB mnu 7 r. T u m mmwww .m S m 1 a e D 17236 "a ,3 Rv 2345 666U 6 9999999 m m 2031 W HHHHHHH mm M nt- N 52 482 imm cw4 U d Std 1844354 nnl 210087 2 UIF J V mm wmfi 1]] l .218 6 UUU. U. 1222333 11Claims, 17 Drawing Figures ll H l |ill ll ll ll ll PATENTEDAUB 15 1912SHEET 1 OF 5 F'IGI Illllllllilllllll FIG. l-L

Jlllllllllllllll L PATENTED 15 1912 3.684; 000

SHEET 2 BF 5 74 66 I56 it 64 64 FIG. 4-R

PATENTEU I973 3,684,000

7 FIG? PATENTEDAUB 15 1972 SHEET 5 OF 5 FIG. 9

MOLD MAKING DEVICE HAVING BLOW NOZZLE This invention relates to themaking of molds for exampleshell molds for making metal castings,particularly to apparatus for applying parting agent to permanentpatterns, delivery of mold forming material into the pattern cavity andremoval of finished molds from the pattern.

In order to help separate finished shell molds from the pattern, thewalls of the cavity which determine and shape the mold are coated with aparting agent such as a silicone oil, which may be applied before eachmold is formed or at intervals in a repetitive process of forming molds.In customary processes the parting agent is sprayed on exposed cavitysurfaces with an open pattern with an air suspension or mist of theparting agent. But the parting agent also coasts the surfaces of theseparation of the pattern. This retains particles of dust or fine sandwhich may be dislodged from the finished molds. Such particles mayprevent the subsequent precise meeting of the mold halves and preventprecise closing of the pattern. To avoid this I provide apparatus whichsprays the parting agent into a pattern which is accurately mated andprecisely closed.

With molds of complicated cavity shapes or with a long series ofcavities, it is sometimes difficult to coat the surfaces evenly and thelast cavity in the series may not have received enough.

One of the objects of the invention is to provide improved apparatuswhich will reliably and evenly apply parting agent to a closed mold.

Another object of the invention is to provide an improved mold coatingapparatus which can be used with sand blowing apparatus of any suitableform and which has coordinated power and control for coordinating thepattern coating apparatus and the sand blowing apparatus.

Another object is to provide improved apparatus for lifting the finishedmolds out of the pattern and for stripping the finished molds from corepins or ejection pins.

' These and other objects of the invention will be understood from thefollowing description and from the accompanying drawings which disclose,for illustration only and not by way of limitation, one form of improved apparatus embodying my invention.

FIG. 1 is a diagrammatic partial front elevation of a pattern and ofblowing devices embodied in my improved machine, at one stage of theprocess of forming a series of shell molds (the sand blowing devicebeing in the inoperative position).

FIG. 1L is a schematic partial left side elevation of the pattern withthe left hand blow-vent nozzle at the stage shown in FIG. 1, at theposition to vent the pattern at the left.

FIG. IR is a schematic partial right side elevation of the pattern withthe right hand blow-vent nozzle at the stage shown in FIG. 1, inposition to blow parting agent into the mold from the right, the sandblowing device being omitted.

FIG. 2 is a partial front elevation corresponding to FIG. 1 at asubsequent position of the machine with the blow-vent nozzles clampedagainst the pattern.

FIG. 3 is an elevation corresponding to FIG. 2 at a later stage of theprocess of forming the molds in which the pattern is blown from theleft.

FIG. 3L is an elevation corresponding to FIG. 1L of the pattern with theleft hand blow-vent nozzle at the stage shown in FIG. 3 and in positionto blow parting agent into the mold from the left.

FIG. 3R is an elevation corresponding to FIG. 1R of the pattern with theright hand blow-vent nozzle at the stage shown in FIG. 3 and in positionto vent the mold at the right.

FIG. 4 is an elevation corresponding to FIG. 2 at a still later stage inthe process of making the molds in which one blow-vent nozzle is out ofthe way and the sand blowing device is in the operative position.

FIG. 4L is an elevation corresponding to FIG. 3L of the pattern with theleft hand blow-vent nozzle at the stage shown in FIG. 4 in position toblock the left end passage into the pattern.

. FIG. 4R is an elevation corresponding to FIG. 3R of the pattern,blow-vent nozzle, and sand blow box in position to blow sand into themold from the right.

FIG. 4R is an elevation corresponding to FIG. 4R at a later stage ofoperation showing the pattern separated and the shell molds ejected fromit in position to be removed from their cores.

FIG. 5 is a fragmentary front elevation, partly in section,corresponding to FIG. 1 showing one form of structure of means forsupporting cores in the pattern and for ejecting finished shell moldsfrom the pattern.

FIG. 6 is an enlarged structural section through one form of pattern formaking tappet cores, taken on the line 6-6 of FIG. 5 which is also onthe line 6-6 of FIG. 7.

FIG. 7 is a structural section of a single cavity of a pattern on theline 7-7 of FIG. 6 which corresponds to the line 7 --7 of FIG. 3-R.

FIG. 8 is a structural section corresponding to FIG. 6 (and on the line8--8 of FIG. 9) of a single cavity in another form of pattern (formaking shell molds for engine valves) showing the core in place.

FIG. 9 is a section on the line 9-9 of FIG. 8.

FIG. It) is a perspective of a pair of molds (one cut away) made in thepattern of FIGS. 6 and 7.

DEFINITIONS As used herein pressure gas means any gas under pressure,including, without limitation, air and superheated steam.

Sand means any granular mold forming material adapted to be packed intoa cavity and cured to form a mold. One example, without limitationissilica sand, the grains of which have been coated with a curablebinder.

Mold means any structure into or around which molten metal may be cast.This includes both hollow molds into which metal may be cast, and coresaround which metal is cast.

The invention provides an improved machine which is particularly adaptedto making the cores 2% shown in FIG. 10 or hollow molds, made in space22 in the pattern of FIG. 8. The cores 2!) are used in casting hydraulicvalve lifters (tappets) of the form shown in the U.S. Pat. to Thompson,No. 3,412,721, Nov. 26, 1968. These cores are formed with a vent space24 by a permanent core or pin. The hollowmold of FIG. 9 is for castingan engine valve as shown in the U.S. Pat. to Thompson No. 3,395,747,Aug. 6, 1968, and is made over a permanent core 26 of the form of thefinished valve casting.

As shown in FIGS. 1-3 a pattern having two separable halves 30, 32mounted on supporting bars 34 is provided with a series of generallycylindrical cavities 36 indicated in dotted lines in FIGS. 1, 4 and andin solid lines in FIGS. 6 and 7. The cavities are connected by a passage38 extending entirely through the pattern from one end to the other. Onthe left end of the mold is a blow-vent nozzle 40 keyed to a rotatableshaft 42 which at its right end carries a sleeve 44 to which is keyed asecond blow vent nozzle 46. The sleeve can slide axially but not rotatewith respect to the shaft. The blow vent nozzles can be moved apart tothe position shown in FIG. 1 or moved together to the position shown inFIG. 2 (in which they are clamped against the ends of the pattern) byany suitable control device, herein schematically represented by adouble acting hydraulic cylinder 48 mechanically fixed to the sleeve 44and carrying a piston 50 mechanically connected to the shaft 42 Thecylinder is controlled by hydraulic lines 54 and 56. Superior pressurein the line 54 separates the nozzles as shown in FIG. 1. Superiorpressure in the line 56 clamps the nozzles against the ends of thepattern as shown in FIG. 2. The. lines may be pressurized and timed byany suitable apparatus, for example that shown (FIG. 13) of the US. Pat.to Thompson, No. 3,071,929, Jan. 8, 1963, the disclosure of which isincorporated herein by reference. Connection of the line 56 to the line640a in that patent, pressurized by the cam 628a and connection of theline 54 to the return reservoir at the line 644 will accomplish thisresult.

The nozzles 40 and 46 each consist of a flat plate which as shown inFIGS. 1L and IR has through it a blow opening 58 connected to an airsupply pipe 60 and a vent opening 62. In FIG. 1L and IR the vent openingis indicated diagrammatically by a triangle and the blow opening isindicated by a circle. These openings are disposed on an arc whosecenter is the center of shaft 42 so that as the shaft is rotated theblow openings and vent openings can be swung selectively opposite thepassage 38. The shaft 42 may be rotated with sleeve 44 by a piston 64 ina double acting hydrauliccylinder 66 controlled by lines 68 and 70.Superior pressure in the line 68 moves the piston as far into thecylinder as it can go and places the nozzles 40, 46 in one extremecondition in which the nozzle 46 can blow into the right end of thepassage 38 while the nozzle 40 vents the left end of the passage. Asshown in FIGS. 3L and 3R superior pressure in line 70 tends to move thepiston out of the chamber and place the nozzles in an intermediateposition in which a tail 72 on nozzle 40 is held against a stop 74 setby a spring. This holds the nozzles in position to blow into the leftend of the passage 38 and vent the right end to the passage. Each of thevent openings 62 is provided with a choke or fixed orifice having acontrolling cross section less than the controlling cross section of thepassage 38 so that the desired pressure will be maintained throughoutthe cavity to deposit the required amount of parting agent. Each pipe 60is supplied with a gaseous suspension of parting agent under pressurefrom a source of pressure 76 under the control of a valve 78 operated bya double acting hydraulic cylinder 80 whenever it is desired to blowthrough that particular nozzle.

The nozzle 40 has a second tail 82 which can block the passage 38 at theleft end whenever the nozzle 42 is in the position shown in FIG. 4L. itcan be put in this position whenever an electrical circuit 84 removesthe spring held stop 74 from its stopping position in the path of tail72 shown in FIG. 3L to the passing position shown in FIG. 4L. Theelectrical circuit 84 can be energized at the appropriate time in thecycle of operation by any suitable device such as any suitable switchoperated by the cam shaft 236 in FIG. 5 of the Reissue US. Pat. No.26,218 to Thompson, June 6, 1967 the disclosure of which is incorporatedherein by reference.

It is contemplated that the machine will perform the cycle of operationsshown in FIG. 7 and described in the specification of the applicationfiled by me and Thompson, et al. referred to herein. When the molds havebeen cured, the pattern is separated, the molds are ejected therefromand the molds are stripped from the cores on which they are formed asindicated diagrammatically in FIG. 4R. The shafts 34 may be moved towardand away from each other by double acting hydraulic cylinders actuatedby a hydraulic separating line 92 and a hydraulic closing line 94 whichlines may be pressurized as disclosed in the Reissue patent referred to.When the pattern halves 30 and 32 are separated as shown in FIG. 4R adouble acting hydraulic cylinder 96 may be operated by suitableconnections to the system shown in the Reissue patent to elevate pincore bar 98 (carrying core pins 100) by means of a bell crank lever I02,link I04 and core elevator 1106. Thereafter a stripping fork 168 ismoved from the full line position shown in FIG. 4R to the dotted lineposition underneath the molds M0, the cylinder 96 is pressurized tolower the support 106 and the molds are thereby stripped from the pins.Thereafter the stripping fork 108 may be moved back to its full lineposition and the molds removed in any suitable manner. The strippingfork is moved in and out by any suitable linkage as shown, actuated bythe double acting hydraulic cylinder 112 connected to the system shownin the reissue patent by hydraulic lines 114 and I 16.

FIGS. 5, 6 and 7 show one form of actual structure of the pattern.Pattern halves 36-32 meet along a parting line 118 and may have splitbushings or liners 126 each pair of which mates to form one of thecavities 36. One pin core 100 projects through the connecting passage 38into each cavity 36 to form the vent opening 24 shown in FIG. 10. Thepin cores are supported on studs 124 projecting upwardly from pin corebar 98 attached and connected to an air supply manifold 128 (FIG. 5)secured to the upper end of a pair of guide bars 130 slidable verticallyin a guide 132 and connected to the elevator rod 106. One of the guidebars may be hollow, to form an air supply conduit which feeds air underpressure to the air manifold 128 which in turn feeds it through aconnection 134 to the interior of the pin core bar 98. The latter isperforated to provide air blast nozzles 140, which as the pin core baris raised through the separated pattern parts 30 and 32, blows air overthe pattern surfaces to dislodge any loose sand or dust which may havebeen left thereby by the mold.

The entire structure shown in FIG. 5 and its control apparatus may beduplicated allochirally about a plane represented by the center line C-Lin FIG. 5, this duplication being indicated in FIG. 5 by a second blowvent nozzle 40.

After the pattern has been satisfactorily coated with parting agent sandis blown into the mold. A sand blow box 150 (FIG. 1) constructed andoperated as more fully described in the application referred to by meand Thompson, et al., may be used. This blow box is tilted to theposition of FIG. 1 out of the path of the blow vent nozzle 46 wheneverthe blow-vent nozzles are in any position except that shown in FIGS. 4Land 4R.

When the blow nozzles are in this position however the sand blow box ismoved to the position of FIG. 4 and its sand blow nozzle 152 is pressedagainst the end of the pattern 30, 32. Then sand is blown into thepattern by compressed air supplied to a fitting 154 from a pressuresource 156 under control of a blow valve 158 operated by any suitablehydraulic power and timing cylinder 160. After the pattern is packedwith sand the sand blow box is swung away from the pattern to theposition shown in FIG. 1, and the molds are removed from the pattern asdescribed above and shown schematically in FIG. 4R. Then the pattern isclosed, coated with parting agent again if necessary, and the process isrepeated.

I claim as my invention.

1. A device for making molds comprising in combination a pattern havinga through passage including a mold cavity, a pair of rotatable blow-ventnozzles, one at each end of the passage, for coating the pattern with aparting agent, means for selectively holding the nozzles against thepattern and releasing them, means for supplying the nozzles with agaseous suspension of parting agent, means on one nozzle for blockingone end of the passage through the pattern, means for rotating thenozzles to a first position in which the first nozzle can blow into thepattern while the second nozzle vents the pattern, to a second positionin which the first nozzle vents the pattern while the second nozzle canblow into the pattern, and to a third position in which the secondnozzle blocks the pattern passagewhile the first nozzle is removed fromthe pattern passage, means for flowing sand into the pattern passagewhen the first nozzle is removed, means for opening the pattern, meansfor lifting molds from the pattern, means for stripping the molds fromthe lifting means and a coordinated moving and control mechanism foroperating the nozzle ho1ding means, nozzle rotating means, suspensionsupply means, sand blowing means, pattern opening means, lifting meansand stripping means in a predetermined timed relation.

2. A device for making molds comprising in combination a pattern havinga through passage including a mold cavity, a pair of blow-vent nozzles,one at each end of the passage, each nozzle having a blow opening and avent opening, means for moving the nozzles selectively to a firstposition in which the first nozzle can blow into the passage while thesecond nozzle vents the passage and to a second position in which thefirst nozzle vents the passage while the second nozzle can blow into thepassage and to a third position in which one nozzle blocks the passagewhile the other nozzle is removed from the passage, means for flowingsand into the pattern, means for moving the flowing means to and awayfrom the passage, and coordinated means for moving the nozzles to thethird position and moving the flowing means to the passage.

3. A device for making molds comprising in combination a pattern havinga through passage including a mold cavity, a pair of blow-vent nozzles,one at each end of the passage, each nozzle having a blow opening and avent opening, means for moving the nozzles selectively to a firstposition in which the first nozzle can blow into the passage while thesecond nozzle vents the passage and to a second position in which thefirst nozzle vents the passage while the second nozzle can blow into thepassage and to a third position in which one nozzle blocks the passagewhile the other nozzle is removed from the passage, and means forflowing sand into the passage when the nozzles are in the thirdposition.

4. A device for making molds comprising in combination a pattern havinga through passage including a mold cavity, a pair of blow-vent nozzles,one at each end of the passage, each nozzle having a blow opening and avent opening, means for moving the nozzles selectively to a firstposition in which the first nozzle can blow into the passage while thesecond nozzle vents the passage and to a second position in which thefirst nozzle vents the passage while the second nozzle can blow into thepassage and to a third position in which one nozzle blocks the passagewhile the other nozzle is removed from the passage.

5. A device for making molds comprising in combination a pattern havinga through passage including a mold cavity, a pair of blow-vent nozzles,one at each end of the passage, each nozzle having a blow opening and avent opening whose controlling cross section is less than thecontrolling cross section of the passage, and means for moving thenozzles selectively to positions for blowing into the passage and forventing into the passage, the moving means being so arranged that whenone nozzle can blow into the passage, the other vents the passage.

6. A device for making molds comprising in combination a patternhaving-a through passage including a mold cavity, a pair of blow-ventnozzles, one at each end of the passage, each nozzle having a blowopening and a vent opening, and means for moving the nozzles selectivelyto positions for blowing into the passage and for venting into thepassage, the moving means being so arranged that when one nozzle canblow into the passage, the other vents the passage.

7. A device for making molds comprising in combination a pattern havinga through passage including a mold cavity, a blow-vent nozzle, means formoving the nozzle to a first position for blowing a suspension ofparting agent into one end of the passage and to a second position forventing the passage and to a third position in which the nozzle isremoved from the passage.

8. A device for making molds comprising in combination a pattern havinga through passage including a mold cavity, a nozzle having a blowopening and a vent opening of a controlling cross section less than thecontrolling cross section of the passage, means for moving the nozzle toa first position for blowing a suspension of parting agent into one endof the passage and to a second position for venting the passage.

9. A device for making molds comprising in combination a pattern havinga through passage including a mold cavity, a blow-vent nozzle, means formoving the nozzle to a first position for blowing a suspension ofparting agent into one end of the passage, to a second position forventing the passage, and to a third position for blocking the passage.

10. A device for making molds comprising in combination a pattern havinga through passage including a mold cavity, a pair of rotatable blow-ventnozzles, one at each end of the passage, for coating the pattern with aparting agent, means for selectively holding the nozzles against thepattern and releasing them, means for supplying the nozzles with agaseous suspension of parting agent, means on one nozzle for blockingone end of the passage through the pattern, means for rotating thenozzles to a first position in which the first nozzle can blow into thepattern while the second nozzle vents the pattern, to a second positionin which the first nozzle vents the pattern while the second nozzle canblow into the pattern, and to a third position in which the secondnozzle blocks the pattern passage while the first nozzle is removed fromthe pattern passage, means for flowing sand into the pattern passagewhen the first nozzle is removed, means for opening the pattern, aperforate ejecting support, means for supplying pressure gas to thesupport, means responsive to opening the pattern for moving the supportbetween the separated parts of the pattern to remove finished molds andwash the pattern with pressure gas, means for stripping the molds fromthe lifting means and a coordinated moving and control mechanism foroperating the nozzle holding means, nozzle rotating means, suspensionsupply means, sand flowing means, pattern opening means, and strippingmeans in a predetermined timed relation.

11. A device for making molds comprising in combination a separablepattern having through it a passage including a cavity for making molds,means for blocking one end of the passage and flowing sand into theother end, means for separating the pattern, an ejecting support, meansresponsive to separating the pattern for moving the support to removefinished molds from the pattern, means responsive to moving the supportfor washing the pattern with pressure gas and a coordinated moving andcontrol mechanism for operating in a predetermined timed relation theflowing means and separating means.

1. A device for making molds comprising in combination a pattern havinga through passage including a mold cavity, a pair of rotatable blow-ventnozzles, one at each end of the passage, for coating the pattern with aparting agent, means for selectively holding the nozzles against thepattern and releasing them, means for supplying the nozzles with agaseous suspension of parting agent, means on one nozzle for blockingone end of the passage through the pattern, means for rotating thenozzles to a first position in which the first nozzle can blow into thepattern while the second nozzle vents the pattern, to a second positionin which the first nozzle vents the pattern while the second nozzle canblow into the pattern, and to a third position in which the secondnozzle blocks the pattern passage while the first nozzle is removed fromthe pattern passage, means for flowing sand into the pattern passagewhen the first nozzle is removed, means for opening the pattern, meansfor lifting molds from the pattern, means for stripping the molds fromthe lifting means and a coordinated moving and control mechanism foroperating the nozzle holding means, nozzle rotating means, suspensionsupply means, sand blowing means, pattern opening means, lifting meansand stripping means in a predetermined timed relation.
 2. A device formaking molds comprising in combination a pattern having a throughpassage including a mold cavity, a pair of blow-vent nozzles, one ateach end of the passage, each nozzle having a blow opening and a ventopening, means for moving the nozzles selectively to a first position inwhich the first nozzle can blow into the passage while the second nozzlevents the passage and to a second position in which the first nozzlevents the passage while the second nozzle can blow into the passage andto a third position in which one nozzle blocks the passage while theother nozzle is removed from the passage, means for flowing sand intothe pattern, means for moving the flowing means to and away from thepassage, and coordinated means for moving the nozzles to the thirdposition and moving the flowing means to the passage.
 3. A device formaking molds comprising in combination a pattern having a throughpassage including a mold cavity, a pair of blow-vent nozzles, one ateach end of the passage, each nozzle having a blow opening and a ventopening, means for moving the nozzles selectively to a first position inwhich the first nozzle can blow into the passage while the second nozzlevents the passage and to a second position in which the first nozzlevents the passage while the second nozzle can blow into the passage andto a third position in which one nozzle blocks the passage while theother nozzle is removed from the passage, and means for flowing sandinto the passage when the nozzles are in the third position.
 4. A devicefor making molds comprising in combination a pattern having a throughpassage including a mold cavity, a pair of blow-vent nozzles, one ateach end of the passage, each nozzle having a blow opening and a ventopening, means for moving the nozzles selectively to a first position inwhich the first nozzle can blow into the passage while the second nozzlevents the passage and to a second position in which the first nozzlevents the passage whiLe the second nozzle can blow into the passage andto a third position in which one nozzle blocks the passage while theother nozzle is removed from the passage.
 5. A device for making moldscomprising in combination a pattern having a through passage including amold cavity, a pair of blow-vent nozzles, one at each end of thepassage, each nozzle having a blow opening and a vent opening whosecontrolling cross section is less than the controlling cross section ofthe passage, and means for moving the nozzles selectively to positionsfor blowing into the passage and for venting into the passage, themoving means being so arranged that when one nozzle can blow into thepassage, the other vents the passage.
 6. A device for making moldscomprising in combination a pattern having a through passage including amold cavity, a pair of blow-vent nozzles, one at each end of thepassage, each nozzle having a blow opening and a vent opening, and meansfor moving the nozzles selectively to positions for blowing into thepassage and for venting into the passage, the moving means being soarranged that when one nozzle can blow into the passage, the other ventsthe passage.
 7. A device for making molds comprising in combination apattern having a through passage including a mold cavity, a blow-ventnozzle, means for moving the nozzle to a first position for blowing asuspension of parting agent into one end of the passage and to a secondposition for venting the passage and to a third position in which thenozzle is removed from the passage.
 8. A device for making moldscomprising in combination a pattern having a through passage including amold cavity, a nozzle having a blow opening and a vent opening of acontrolling cross section less than the controlling cross section of thepassage, means for moving the nozzle to a first position for blowing asuspension of parting agent into one end of the passage and to a secondposition for venting the passage.
 9. A device for making moldscomprising in combination a pattern having a through passage including amold cavity, a blow-vent nozzle, means for moving the nozzle to a firstposition for blowing a suspension of parting agent into one end of thepassage, to a second position for venting the passage, and to a thirdposition for blocking the passage.
 10. A device for making moldscomprising in combination a pattern having a through passage including amold cavity, a pair of rotatable blow-vent nozzles, one at each end ofthe passage, for coating the pattern with a parting agent, means forselectively holding the nozzles against the pattern and releasing them,means for supplying the nozzles with a gaseous suspension of partingagent, means on one nozzle for blocking one end of the passage throughthe pattern, means for rotating the nozzles to a first position in whichthe first nozzle can blow into the pattern while the second nozzle ventsthe pattern, to a second position in which the first nozzle vents thepattern while the second nozzle can blow into the pattern, and to athird position in which the second nozzle blocks the pattern passagewhile the first nozzle is removed from the pattern passage, means forflowing sand into the pattern passage when the first nozzle is removed,means for opening the pattern, a perforate ejecting support, means forsupplying pressure gas to the support, means responsive to opening thepattern for moving the support between the separated parts of thepattern to remove finished molds and wash the pattern with pressure gas,means for stripping the molds from the lifting means and a coordinatedmoving and control mechanism for operating the nozzle holding means,nozzle rotating means, suspension supply means, sand flowing means,pattern opening means, and stripping means in a predetermined timedrelation.
 11. A device for making molds comprising in combination aseparable pattern having through it a passage including a cavity formaking molds, means for blocking one end of the passage and fLowing sandinto the other end, means for separating the pattern, an ejectingsupport, means responsive to separating the pattern for moving thesupport to remove finished molds from the pattern, means responsive tomoving the support for washing the pattern with pressure gas and acoordinated moving and control mechanism for operating in apredetermined timed relation the flowing means and separating means.